1. Field of the Invention
This invention pertains to a safety device for reducing the likelihood of accidental electrocution caused by an electrical appliance that is typically used in the vicinity of water, and, more particularly, to a safety device for an electrical appliance, such as a hair dryer or shaver, having a delayed-action alarm system that activates within a predetermined time period when an idle appliance that has been turned off is coupled to a power source.
2. Background of the Prior Art
Many hand-held home appliances, such as hair dryers, electric shavers, or similar electrical appliances, present an undue risk of injury when used near water and connected to an electrical outlet. This is particularly true even when the appliance is turned off. Should an appliance that is turned off, but plugged into a household power supply, accidentially fall into a bathtub or a wash basin while a person has a portion of his body in contact with the water in the tub or basin, the person could be electrocuted or otherwise injured. Electrocution results from the conductors of the power cord or the on-off switch coming into contact with the water.
Most home appliances operate on alternating current and include a power cord adapted to plug into an alternating current wall outlet. The conductors of the power cord connect to an on-off contact switch in the appliance. The switch is manually operated for making and breaking electrical connection with a motor, a heater element, or an electrical circuit in the appliance. Within the switch, the electrical connections are accomplished through conductive contacts which, if placed in water, present the hazardous condition just described. Some switches used in home appliances are double-poled, single-throw and operate to break both lines of an a.c. power source, whereas other switches are single-pole, single-throw and break only one of the a.c. lines. In the latter type of switch, if the "hot" line is not broken, the appliance, if submerged in water, may still provide a complete circuit path to ground, such as through the plumbing pipes of the tub or basin. Thus, for increased safety, it is desirable to disconnect the appliance from the power supply.
Some manufacturers of appliances place warning labels on their product instructing the user to disconnect the appliance when not in use, but such warnings often go unheeded. Attempts might be made to reduce the likelihood of accidental electrocutions by insulating and/or waterproofing electrical circuits of the appliance, however, such waterproofing or insulating may not be justified in view of the costs involved in doing so. Sometimes, after prolonged use, the insulation or waterproofing becomes ineffective.
One solution to this problem is provided by the use of a ground fault interrupter placed in the household electrical line. If an appliance falls into a filled basin or tub, then the ground fault interrupter, through a fast-acting circuit breaker, senses the ground fault current and disrupts power to the appliance. Even though the ground fault interrupter has met with great success, many older homes and buildings do not contain such a device. Further, there are situations where the appliance may be used near water and plugged into a socket that is not protected by a ground fault interrupter.
In other situations, the on-off switch of the appliance is located in the power cord, in which case, if the appliance falls into the water, current will not flow therethrough. But in some instances, the electrical outlet itself may be located in close proximity of the water basin. In this case, the switch contacts themselves can still fall into the basin or tub and come into contact with the water. It would appear, then, to obviate accidental electrocutions, or at least to reduce their likelihood, the on-off switch might be placed directly at the wall plug of the power cord next to the electrical receptacle. But such a design would impose an inconvenience on the user with some types of electrical appliances where frequent on-off use is desired, such as a shaver, hair dryer or electric toothbrush.
It is therefore an objective of this invention to reduce the likelihood of such accidental electrocutions which might occur with electrical appliances generally used around water.
It is another objective of the present invention to provide a warning system for such hand-held electrical appliances, which warning system permits convenient, frequent on-off use often desired with such appliances.